Conventional retaining walls are used to secure earth embankments against sliding and slumping. Retaining walls are made of various types of concrete, solid masonry, wood ties, bricks, and blocks of stone and concrete. The blocks are placed in rows and superimposed on top of each other to form a wall. Examples of blocks used in the construction of retaining walls are shown by Heinzmann in U.S. Pat. No. 4,229,123 and Scheiwiller in U.S. Pat. No. 4,524,551. These patents disclose a plurality of block elements stacked on each other and located in rows to form retaining walls. The block elements have tongue and groove structures which allow adjacent rows of blocks to interengage each other to form generally upright walls. The block elements also have hollow interiors with open tops and bottoms for accommodating soil and plants. Solid walls use considerable amounts of material. They are also expensive and require considerable time and labor to construct. Block walls are satisfactory where the pressure behind the wall is not too great or the slope not to steep as the blocks are not connected together. The disadvantages of the prior retaining walls are overcome with the wall blocks and wall structure of the present invention.